1. Field of the Invention
The present invention relates to a radiation conversion panel for recording radiation image information by being irradiated with a radiation and for allowing recorded radiation image information to be read by being scanned with reading light, and an apparatus for and a method of reading radiation image information from such a radiation conversion panel.
2. Description of the Related Art
There has heretofore been known a light-reading-type radiation image information reading apparatus for applying a radiation to a subject, storing the radiation that has passed through the subject in a semiconductor radiation conversion panel, and thereafter scanning the radiation conversion panel with reading light to acquire radiation image information as electric charge information from the position where the radiation conversion panel is scanned for the purpose of medically diagnosing the subject (see Japanese Laid-Open Patent Publication No. 2003-210443). Another known radiation image information reading apparatus employs a radiation conversion panel in the form of a stimulable phosphor panel which emits stimulated light depending on stored energy when it is irradiated with stimulating light such as visible light. When the stimulable phosphor panel is irradiated with stimulating light such as a laser beam or the like, the stimulable phosphor panel emits stimulated light representing radiation image information that is photoelectrically read (see Japanese Laid-Open Patent Publication No. 2005-283798).
With the radiation image information reading apparatus which employs the radiation conversion panel, it is difficult to read all the radiation image information recorded in the radiation conversion panel, and part of the radiation image information tends to remain in the radiation conversion panel. If the radiation conversion panel with remaining radiation image information is used again, then the remaining radiation image information acts as noise, producing fog on new radiation image information. Therefore, it is necessary to perform a corrective process for removing the remaining radiation image information from the new radiation image information.
According to Japanese Laid-Open Patent Publication No. 2003-210443 and Japanese Laid-Open Patent Publication No. 2005-283798, after radiation image information G1 (see FIG. 15A of the accompanying drawings) is read from a radiation conversion panel, next radiation image information G2 is recorded on the radiation conversion panel. Then, when the radiation image information G2 is read from the radiation conversion panel, the radiation image information G2 that is read contains remaining radiation image information G1′ (see FIG. 15B of the accompanying drawings) which is a residue of the past radiation image information G1. The read radiation image information G2 is stored in a memory. Then, the residual radiation image information G1′ that is calculated from the past radiation image information G1 is subtracted from the radiation image information G2, thereby producing desired radiation image information G2.
For reading the radiation image information from the radiation conversion panel in the light-reading-type radiation image information reading apparatus, the radiation conversion panel is scanned with reading light or stimulating light in the direction indicated by the arrow C. The radiation image information G2 read from the radiation conversion panel cannot properly be corrected unless the relationship between the position where radiation conversion panel is scanned with the reading light or stimulating light and the radiation image information read from the scanned position.
For example, if the scanning speed of the reading light or stimulating light for reading the past radiation image information G1 from the radiation conversion panel and the scanning speed of the reading light or stimulating light for reading the next radiation image information G2 from the radiation conversion panel are different from each other, or if the positions where the radiation image information G1, G2 starts being read are different from each other, then the residual radiation image information G1′ cannot properly be subtracted from the radiation image information G2 at the corresponding position, and hence the radiation image information G2 cannot properly be corrected.